1. Field of the Invention
The present invention is generally concerned with electrical units which, for fixing them to a support of any kind, for example a wall, and for supplying them with power, plug into a mount attached to the support.
2. Description of the Prior Art
It is more particularly aimed at electrical units of this kind that include a hollow base the back of which is adapted to be plugged into the mount and has a back wall and which is removably closed at the front by at least one cover, with, internally, between the back wall and this cover, at least one housing in which there is at least one active member, for example a connecting terminal, that is liable to be live when the assembly is plugged into the mount.
This is the case, in particular, with certain self-contained emergency lighting units.
To alleviate the consequences of failure of the mains electrical power supply, these self-contained emergency lighting units include, internally, within their hollow base, a storage battery which is connected at all times to live connection terminals in order to keep it charged.
When it is necessary to obtain access to the storage battery, for example to remove it and/or to change it, among other feasible maintenance operations, there is the risk, for the operator, of unintentional contact with these connecting terminals, which is to the detriment of safety.
In some implementations the housing in which the storage battery is disposed is accessible from the front.
It is, in practice, a housing which extends over only part of the hollow base and which is closed by a particular cover to which is attached a cassette carrying the storage battery, whereas the other part of the hollow base, in which other units are housed, is closed by another cover, separate from the first, and removal of which is dependent on removal of the first cover.
Apart from the fact that, for the reasons given, this arrangement is not satisfactory from the safety point of view, it leads to the provision of two covers, which is to the detriment of the cost.
In other implementations, the housing in which the storage battery is disposed is accessible only from the rear of the hollow base and to obtain access to it the hollow base must first be demounted, which systematically isolates it, which is to the benefit of safety.
However, to hold the storage battery in its housing, the housing must be closed at the rear by a particular cap which is additional to the front cover or covers, and this is to the detriment of the cost.
A general object of the present invention is an arrangement satisfying safety requirements at the lowest cost.